CN103103765B - Self-emulsifying wet-scratch-resistant leather top coat finishing agent and preparation method thereof - Google Patents

Abstract

The invention relates to a self-emulsifying wet rubbing resistant leather top layer coating agent and a preparation method of the self-emulsifying wet rubbing resistant leather top layer coating agent. The wet rubbing resistant leather top layer coating agent is formed by mixing the following raw materials: epoxy polysiloxane modified gelatin, solvent absolute ethyl alcohol and acetone, wherein the volume ratio of the absolute ethyl alcohol to the acetone is 3:7; and the proportion of the using amount of the epoxy polysiloxane modified gelatin to the solvent is 1g/ml. The structural formula of the epoxy polysiloxane modified gelatin is that FORMUAL, wherein n is an integer from 7 to 50. Compared with the prior art, the self-emulsifying wet rubbing resistant leather top layer coating agentis extremely high in wet rubbing resistance; and after being coated on leather, soft handfeel and high water steam permeation performance can be achieved.

Description

Self-emulsifying wet-scratch-resistant leather top coat finishing agent and preparation method thereof

Technical field:

The invention relates to a leather finishing agent and a preparation method thereof, in particular to a self-emulsifiable leather top-coat finishing agent, in particular to a self-emulsifying, wet rub-resistant, organic solvent-resistant, and oxidation-resistant leather top-coat finishing agent. method.

Background technique:

At present, wet-scratch-resistant leather top-coat finishing agents in the synthetic leather market have become a popular trend in the future, and are widely used in clothing, car accessories, and luggage products.

After the general leather top coating is applied to the leather, it needs to be prepared by adding other reagents and emulsifiers after emulsification. However, the self-emulsifying wet rub-resistant leather top coating is different. It is mainly composed of gelatin and epoxy polysiloxane monomers. Synthesized with surfactants, after the gelatin material is prepared, it forms latex particles with a core-shell structure with polysiloxane as the core and gelatin as the shell, which can be directly painted on the top layer of leather, and placed at room temperature for 2 to 6 hours. A continuous coating film can be formed by demulsification. Using the low surface performance characteristics of silicone, the silicone segment is enriched on the surface, and has the advantages of good flame resistance, good weather resistance, good water resistance, thermal stability and good air permeability. .

With the wide application of leather materials, the performance requirements for top coating agents such as scratch resistance, oxidation resistance, weather resistance, and water vapor permeability are also increasing. However, the currently developed scratch-resistant wet-type leather finishing agents have unstable wet-scratch performance, and hinder the water vapor permeability of the leather, and the overall performance is not high.

Invention content:

The purpose of the present invention is to overcome the shortcomings of the existing anti-scratch leather top layer finishing agent, to provide a self-emulsifying type wet-scratch-resistant leather top layer finishing agent and its preparation method, which not only has very good anti-scratch performance, but also can be applied on leather Finally, it can achieve a soft feel and excellent water vapor permeability.

The technical scheme that the present invention takes is:

Self-emulsifying wet-scratch-resistant leather top finish, which is made by mixing the following raw materials: gelatin modified by epoxy polysiloxane, solvent absolute ethanol and acetone; the volume ratio of absolute ethanol and acetone is 3:7, epoxy The ratio of polysiloxane-modified gelatin to solvent is 1 g/ml.

The gelatin structural formula of described epoxy polysiloxane modification is:

Wherein, n is an integer of 7-50.

The preparation method of the above-mentioned self-emulsifying type wet-scratch-resistant leather top coat finishing agent comprises the steps as follows:

(1) Dissolve gelatin in water to prepare an aqueous solution, adjust its temperature at 40-70°C, and adjust the pH of the system to 6-12; stir, and after the pH value of the system is stable, add surfactant, the amount of surfactant is 2-20% of the mass of gelatin; continue to stir, while adding epoxy polysiloxane containing Si-O-Si repeating units in batches or continuously, the amount of epoxy polysiloxane is 1.5-10 times the mass of gelatin, After reacting at 40~70℃ for 12~24h, epoxy polysiloxane modified gelatin is obtained;

(2) Add epoxy polysiloxane-modified gelatin to a mixed solvent of absolute ethanol and acetone, and mix well by ultrasonication for 1-3 minutes.

Self-emulsifying wet rub resistant leather top coat finish is applied directly to the top layer of the hide and allowed to dry naturally.

The mass concentration of the gelatin solution in the above step (1) is 2-16%, and the molar ratio of the primary amine groups contained in the gelatin molecule itself to the epoxy group is 0.5-5:1, wherein the primary amine groups contained in the gelatin molecule itself The molar weight of the base is measured by a primary amino group tester [using the method of patent CN102393466A]. The inventors have found through multiple tests that when the molar ratio of primary amino groups to epoxy groups reaches the above ratio, the grafting rate of silicone is optimal. The pH of the gelatin solution was adjusted with 3 mol/L sodium hydroxide. The surfactant is one or more of anionic surfactants, cationic surfactants and nonionic surfactants. Anionic surfactants include alkyl sulfates, alkyl sulfonates, and alkylbenzene sulfonates, and the length of the alkyl carbon chain is 8-16. Cationic surfactants include alkyltrimethylammonium bromide and alkylhydroxyethylmethylammonium bromide, and the length of the alkyl carbon chain is 8-16. Nonionic surfactants, including polyoxyethylene type, polyol type, alkanolamide type, and nonionic fluorocarbon surfactants. The epoxy polysiloxane containing Si-O-Si repeating unit has the following structural formula:

Wherein, n is an integer of 7-50, and the molecular weight of epoxy polysiloxane is 200-5000.

The present invention adopts a special type of organosilicon monomer: epoxy polysiloxane. After research and experiment exploration by the inventor, it is found that this type of long-chain epoxy polysiloxane can change the type and The length and the composition and ratio of multiple chain segments can also give gelatin more excellent performance, design product structure, and synthesize products that can meet various needs; using epoxy groups on epoxy polysiloxane monomers, The structure-stabilized gelatin coating material is directly prepared by chemical modification; the polysiloxane material is physiologically inert, non-toxic, and odorless, and can contribute to the clean production of leather.

To sum up, compared with the prior art, the present invention not only has excellent abrasion resistance, but also can achieve soft hand feeling and excellent water vapor permeability after being painted on the leather.

Description of drawings

Fig. 1 is the infrared spectrogram of gelatin;

Fig. 2 is the infrared spectrogram of modified gelatin;

Fig. 3 is the DSC spectrogram before and after epoxy polysiloxane modified gelatin;

Figure 4 is the TG spectra before and after epoxy polysiloxane modified gelatin.

Detailed ways:

The self-emulsifying anti-scratch leather top layer finishing agent of the present invention will be further described in conjunction with the examples below.

The primary amino group content in the gelatin molecule is measured with a primary amino group detector [using the method of patent CN102393466A];

Epoxy polysiloxane is synthesized by anionic polymerization technology (belongs to the prior art);

The product was refluxed in chloroform solvent for 48 hours to remove unreacted epoxy polysiloxane;

The polymer structure was characterized by nuclear magnetic, infrared, and X-ray photoelectron spectroscopy;

The glass transition temperature (Tg) was determined by a differential calorimetry scanner;

The water resistance test procedure of the product is as follows: soak a certain amount of product in double distilled water at room temperature, take it out every 1 hour, dry it in an atmospheric oven at 104°C for half an hour, weigh the quality, and after 24 hours, raise the water bath When the temperature reaches 40°C, continue to soak the product, dry and weigh after 1 hour, raise the temperature of the water bath to 50°C, continue to soak the product, dry and weigh after 1 hour, and calculate the dissolution rate by mass loss;

The test procedure of the product's resistance to organic solvents is: soak a certain amount of product in an organic solvent at room temperature, take it out every 1 hour, dry it in an atmospheric oven at 104°C for half an hour, weigh the mass, continue for 24 hours, and pass the mass Loss calculation dissolution rate;

The contact angle was measured with a contact angle meter.

Example 1:

Add 12 grams of gelatin (accounting for 11.76% of the total mass) and 85 grams of deionized water into a three-necked reaction flask equipped with a thermometer socket, a sampling port, and a condenser socket, stir and heat to 65 °C, and after the gelatin is completely dissolved, add 0.5 mL, 3 mol/liter of sodium hydroxide, adjust the reaction pH to be 9.0, add 5.0g sodium lauryl sulfate, sodium dodecylbenzenesulfonate and sorbitol mixed surfactant (wherein sodium lauryl sulfate 55% (w/w), sodium dodecylbenzenesulfonate 20% (w/w), sorbitol 25% (w/w)) as an emulsifier (4.90% of the total mass), continue After stirring until the emulsifier is completely dissolved, add epoxy polysiloxane (Mw=1000) continuously or in batches, the reaction starts, and the content of primary amino groups in the system does not change after 24 hours of reaction, so stop stirring and heating.

The dissolution rate of the product in deionized water is 43%. The dissolution rate of the product in organic solvents ethanol, acetone, and chloroform is 0.5%. The contact angle of the modified gelatin film is greater than 90°. The infrared, DSC, and thermogravimetric analysis curves of the products before and after gelatin modification are shown in Figures 1-4.

In the infrared spectrum of epoxypolysiloxane-modified gelatin (Figure 2), there appeared 3 new bands that were not found in the infrared spectrum of collagen peptides, and their attributions were as follows: (1) The peak at 802cm ^-1 was Rocking vibration absorption peak of CH in Si-CH ₃ , which is one of the characteristic peaks of polydimethylsiloxane; (2) The peak appearing at 1261 cm ^-1 is the symmetrical deformation bending vibration absorption peak of CH in Si-CH ₃ , which is also one of the characteristic peaks of polydimethylsiloxane; (3) The peak at 2963cm ^-1 is the CH stretching vibration absorption peak. The three characteristic absorption peaks of Si-CH ₃ appearing in the spectrogram indicate that the epoxy group in PDMS-E has reacted with the primary amino group on the collagen polypeptide.

It can be seen from the DSC spectra before and after gelatin modified by epoxy polysiloxane that the Tg of the raw gelatin film is 215.7°C, and the Tg of the modified gelatin film is reduced to 187.6°C; grafted polysiloxane.

From the TG spectra before and after epoxy polysiloxane modified gelatin, it can be seen that the raw material gelatin film begins to decompose around 215°C, and the decomposition temperature of gelatin modified by PDMS-E rises to around 240°C, indicating that the product is thermally stable. Stability is significantly improved.

Take 10.0 grams of prepared modified gelatin, add 10 mL of a mixed solvent of absolute ethanol and acetone, wherein the volume ratio of absolute ethanol to acetone is 3:7, ultrasonication for 1 minute, and after mixing the organic solvent and the modified gelatin evenly, Apply directly to the top layer of the leather, and test the performance of the leather after 72 hours of natural drying.

The technical performance of the self-emulsifying type anti-scratch wet type leather top coat finishing agent of the present invention obtained by the above steps is shown in the following table:

As can be seen from the above table, compared with the prior art level, the self-emulsifying anti-scratch type leather top coating agent of the present invention improves the cohesive force index and reduces the Swelling rate in water and toluene.

In addition, compared with the existing level, the self-emulsifying anti-scratch and moisture-resistant leather top layer finishing agent of the present invention can maintain the soft feel of the leather after being painted on the leather, and has better water vapor permeability.

Example 2:

Add 12 grams of gelatin (accounting for 11.76% of the total mass) and 85 grams of deionized water into a three-neck reaction flask equipped with a thermometer socket, a sampling port, and a condenser socket, stir and heat to 65 °C, and after the gelatin is completely dissolved, add 0.5 mL, 3 mol/liter of sodium hydroxide, adjust the reaction pH to be 9.0, add 5.0g sodium dodecyl sulfate, sodium dodecylbenzenesulfonate and sorbitol mixed surfactant (wherein dodecylsulfonic acid Sodium is 55% (w/w), sodium dodecylbenzenesulfonate is 20% (w/w), sorbitol is 25% (w/w)) as an emulsifier (4.90% of the total mass), Continue to stir until the emulsifier is completely dissolved, then add epoxy polysiloxane (Mw=1000) continuously or in batches, the reaction starts, and the content of primary amino groups in the system does not change after 24 hours of reaction, so stop stirring and heating.

Take 10.0 grams of prepared modified gelatin, add 10 mL of a mixed solvent of absolute ethanol and acetone, wherein the volume ratio of absolute ethanol to acetone is 3:7, ultrasonication for 1 minute, and after mixing the organic solvent and the modified gelatin evenly, Apply directly to the top layer of skin and allow to dry for 72 hours.

Claims (5)

1. Self-emulsifying type wet-scratch-resistant leather top coat finishing agent is characterized in that, is mixed by following raw material: epoxy polysiloxane modified gelatin, solvent dehydrated alcohol and acetone; The volume ratio of dehydrated alcohol and acetone is 3:7, the ratio of the epoxy polysiloxane modified gelatin consumption to the solvent is 1 g/ml; the epoxy polysiloxane modified gelatin structural formula is:

Epoxy polysiloxane modified gelatin polymer Wherein, n is an integer of 7-50. 2. the preparation method of self-emulsifying type wet rubbing resistance leather top layer finishing agent described in claim 1 is characterized in that, comprises steps as follows: (1) Dissolve gelatin in water to prepare an aqueous solution, adjust its temperature at 40-70°C, adjust the pH of the system to 6-12; stir, and after the pH value of the system is stable, add surfactant, the amount of surfactant is 2-20% of the mass of gelatin; continue to stir, while adding epoxy polysiloxane containing Si-O-Si repeating units in batches or continuously, the amount of epoxy polysiloxane is 1.5-10 times the mass of gelatin, After reacting at 40-70°C for 12-24 hours, epoxy polysiloxane-modified gelatin is obtained; (2) Add epoxy polysiloxane-modified gelatin to a mixed solvent of absolute ethanol and acetone, and mix well by ultrasonication for 1-3 minutes. 3. The method for preparing a self-emulsifying wet-scratch-resistant leather top coating according to claim 2, wherein the mass concentration of the gelatin solution in step (1) is 2 to 16%, and the primary amine contained in the gelatin molecule itself The molar ratio of epoxy groups to epoxy groups is 0.5-5:1. 4. the preparation method of self-emulsifying type wet-scratching resistant leather top coat finishing agent according to claim 2 is characterized in that, described surfactant is anionic surfactant, cationic surfactant, nonionic surfactant One or more of the agents; anionic surfactants are alkyl sulfates, alkyl sulfonates, or alkylbenzene sulfonates, and the length of the alkyl carbon chain is 8 to 16; cationic surfactants are alkyl Trimethyl ammonium bromide, or alkyl hydroxyethyl methyl ammonium bromide, the length of the alkyl carbon chain is 8-16; the non-ionic surfactant is polyoxyethylene type, polyol type, alkyl alcohol amide type , or nonionic fluorocarbon surfactants. 5. The preparation method of the self-emulsifying type wet-scratch-resistant leather top coat finishing agent according to claim 2, it is characterized in that, the described epoxy polysiloxane containing Si-O-Si repeating unit has following structural formula: Wherein, n is an integer of 7-50, and the molecular weight of the epoxy polysiloxane is 200-5000.

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